Integration with dhcpc client

[codin86]

ifupdown2, currently uses "dhclient" to obtain/renew an IP address. ISC has deprecated this client (https://www.isc.org/blogs/isc-dhcp-eol/) and some distributions have suggested using "dhcpc" as an alternative. Is there any plan on supporting alternative dhcp clients ?

Thank you,

[christoph-heiss]

I just want to mention my open PR #347 here, which would add dhcpcd as another DHCP client option.